Orthogonal Frequency-Division Multiplexing (OFDM) is widely used in future communication systems as a basic technology for the air interface.
In the modulation scheme of OFDM, .multi-user multiplexing and multiple access are achieved by using a number of orthogonal sub-carriers in one OFDM symbol. In OFDM systems, sub-carriers allocated for different users in the same cell are orthogonal to each other, thereby avoiding multi-access interference. However, when adjacent cells operate on the same frequency, users between the cells, especially those who at edges of the cells, will suffer co-channel interference, which leads to a severe deterioration of in communication quality of the users.
To solve the problem above, “Block Repeat Division Multiple Access” is proposed as a new and efficient multiple access scheme. Information transmission based on Block Repeat (BR) is referred to as block repeat transmission. Multiplexing based on block repeat is referred to as Block Repeat Division Multiplexing (BRDM). Multiple access based on block repeat is referred to as Block Repeat Division Multiple Access (BRDMA). The combination of BRDMA and OFDM can be referred to as Block Repeat-Orthogonal Frequency-Division Multiplexing (BR-OFDM) or Block Repeat-Orthogonal Frequency-Division Multiple Access (BR-OFDMA).
In BR-OFDM, a data block unit is modulated and mapped into a basic Block Unit (BU); the basic block unit is weighted and repeated according to the number of modulation repetitions and a group of repeated block units are obtained. By multiplying of the data block unit in the basic block unit by a group of weighting factors and repeat modulation, a group of repeated block units can be obtained, and thereby realizing weighting and repetition of a group of basic block units. The number of modulation repetitions is referred to as a Repeat Factor (RF), and the set of weighting factors are referred to as a block repeat weighting factor sequence, or a Repeat Code (RC) sequence. The time-frequency resource taken by a repeat block unit is referred to as a Block repeat Resource Block (BRB) which can carry one data block; multiple BRBs constitute a Block repeat Resource Block Group (BRBG) corresponding to multiple data blocks.
When multiple users share the same time-frequency resource to transmit repeated block units, different RC sequences are used for each user in weighting. The receiver can separate repeated block units of different users according their unique RC sequences. Therefore, interference between users of adjacent cells operating on the same time frequency recourses can be reduced, and reliability of signal transmission can be improved.
However, there is no explicit BRDMA based resource allocation/management method been proposed.